This invention relates to the inflation of cuffs of endotracheal tubes, being addressed generally to the same problems as is my prior U.S. Pat. No. 3,565,079.
The inflated cuff of an endotracheal tube forms a seal with the trachea, serving, during the inspiration phase of the respiratory cycle, to maintain pressure in the lungs, and during all phases, serving to block aspiration of liquids or solids from the mouth into the lungs.
As is well known, it is desirable for the cuff inflation pressure to be of low value consistent with maintenance of a good seal. The lower the pressure, the lesser the danger of damage to the tracheal tissue due to blockage of blood flow, etc. Also, it is desirable to achieve this inflation on an automatic basis, without opportunity for error by personnel administering the tube.
My prior patent, mentioned above, sought to achieve the low inflation pressure automatically using the breathing air from the respirator as the source of pressure. But difficulties with constructions shown in that patent have been encountered, relating to loss of sealing pressure during expiration and to design constraints inherently present. Though such difficulties may be overcome, no commercial product has yet resulted.
For other suggestions dealing with cuff inflation see for instance U.S. Pat. Nos. 3,504,676; 3,529,596 and 3,731,691.